chapter9 - Link design

Example 9.4.1, page 9-8

In [2]:
from __future__ import division
output=13       #laser output
sensitivity=-31     #APD sensitivity
coupling_loss=0.5 
L=80    #length in km
sl=0.1  #loss correspond to one splice in dB
fl=0.35     #fiber loss in dB/km
noise=1.5 
allowed_loss=output-sensitivity 
splices_loss=(L-1)*sl 
fiber_loss=L*fl 
margin=allowed_loss-(splices_loss+fiber_loss+coupling_loss+noise) 
print "Final margin is %.1f dB." %margin

Final margin is 6.1 dB.

Example 9.6.1, page 9-12

In [6]:
from numpy import sqrt
L=10 
ts=10 
tD=8 
tmod=L*6 
tt=L*2 
Tsys=1.1*sqrt(ts**2+tmod**2+tt**2+tD**2) 
Bt=0.7/Tsys 
Bt=Bt*10**3 
print "Maximum bit rate for link using NRZ data format is %.2f Mbits/sec." %Bt 
#calculation error in the book.

Maximum bit rate for link using NRZ data format is 9.86 Mbits/sec.